Optical fibres are being used to an ever increasing extent as transmission media in the field of telecommunications and data communications. The use of light signals for communication can result in very fast data transmissions.
Prior publications U.S. Pat. No. 5,265,510, U.S. Pat. No. 5,179,548 and EP-A1 677 936 describe different methods of rectifying cable breaks in optical bus networks. In brief, the protective system involves connecting to the various system nodes one spare fibre in the case of unidirectional communication and two spare fibres in the case of bidirectional communication, in a manner similar to the standard connections but separated physically therefrom. Communication on the spare fibre/s is commenced when a standard fibre has broken at some point or other.